Coordinated Binding of Single-Stranded and Double-Stranded DNA by UvsX Recombinase

Saint Louis University, United States of America
PLoS ONE (Impact Factor: 3.23). 06/2013; 8(6):e66654. DOI: 10.1371/journal.pone.0066654
Source: PubMed


Homologous recombination is important for the error-free repair of DNA double-strand breaks and for replication fork restart. Recombinases of the RecA/Rad51 family perform the central catalytic role in this process. UvsX recombinase is the RecA/Rad51 ortholog of bacteriophage T4. UvsX and other recombinases form presynaptic filaments on ssDNA that are activated to search for homology in dsDNA and to perform DNA strand exchange. To effectively initiate recombination, UvsX must find and bind to ssDNA within an excess of dsDNA. Here we examine the binding of UvsX to ssDNA and dsDNA in the presence and absence of nucleotide cofactor, ATP. We also examine how the binding of one DNA substrate is affected by simultaneous binding of the other to determine how UvsX might selectively assemble on ssDNA. We show that the two DNA binding sites of UvsX are regulated by the nucleotide cofactor ATP and are coordinated with each other such that in the presence of ssDNA, dsDNA binding is significantly reduced and correlated with its homology to the ssDNA bound to the enzyme. UvsX has high affinity for dsDNA in the absence of ssDNA, which may allow for sequestration of the enzyme in an inactive form prior to ssDNA generation.

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Available from: Scott W Morrical, Aug 14, 2015
    • "Alternatively, recovery from dsDNA may involve ligand-induced allosteric effects on the DNA-pairing protein itself. This is observed with the T4 UvsX protein, in which ATPase-inactive complexes on dsDNA are rapidly activated for DNA strand exchange by the addition of homologous , but not of heterologous, ssDNA (Maher and Morrical 2013). "
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